Gadolinium contrast enhanced T1-weighted (gT1w) MRI images of the internal acoustic meati have long been considered the gold standard in the diagnosis of vestibular schwannoma (VS). However, the addition of contrast to the MRI examination increases the cost and time to perform the test and carries a risk of inducing contrast-related adverse reactions. Further, contrast is contraindicated in some patient groups, such as those with severe renal impairment. With MRI IAM forming part of standard screening for CPA lesions in most patients with unilateral hearing loss and/or tinnitus, a high volume of normal studies are undertaken: only 3-4% demonstrate VS. In this article, Dang and colleagues collate the evidence that has been accumulating over the past few years on the use of high-resolution non-contrast T2-weighted (nT2w) MRI as an alternative to gT1w MRI for the screening of patients for VS. They report that the use of nT2w MRI over gT1w maintains a high sensitivity and specificity for detecting VS whilst reducing the time taken to perform the scan to approximately 10 minutes, and halving the cost (to $560/scan); this has been equated to savings of $107,000 and 99.75 hours over the course of a year in one institution. However, compared with gT1w scans, nT2w MRI has some limitations in the ability to detect inflammatory, infectious, or malignant conditions, and a further gT1w MRI may be required to characterise abnormalities found on nT2w scans. Non-contrast T2w MRI may therefore function as a good screening tool in new patients with uncomplicated asymmetrical hearing loss and/or tinnitus, with gT1w MRI used for characterisation of abnormalities detected on nT2w imaging, or in patients where an alternative infectious/inflammatory or malignant intracranial pathology is suspected.
Do we need contrast MRI when screening for vestibular schwannoma?
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